Useful bits? a spare set of wheel bearings and seals, enough for two wheels. Spare bulbs. BIG toolkit. A torch. Spare batteries. Etc, Etc.................
But would it make that much difference, temperature wise? The air from inside would cool down quite quickly with the velocity of passing through a relatively small bore pipe. Its certainly an interesting thought.
Don't think so, as I think they're incorporated into the front mudguards. I've got some D1 sidesteps if you're near Leicester. Be glad to be rid of them.
Purely your choice re. chipping, but I think there may be insurance probs. Also, never had any trouble towing with any D1 or D2 I've used. Just find the best one you can.
When my transfer box went ping that happened suddenly too. Could be that? The fact you have no drive even with difflock engaged would suggest Tbox, or possibly Gbox. Not good news I'm afraid.